Water is the lifeblood of sustainable habitation, and no more so is it crucial than in desert societies. One of this year's winners of the <a href="http://inhabitat.com/2010-winners-of-the-aga-khan-award-for-architecture/">Aga Khan Award for Architecture</a> is not a building complex, but remarkably, an entire ecosystem. Located in Riyadh, the capital of<a href="http://inhabitat.com/saudi-biome-concept-could-be-worlds-largest-biosphere/"> Saudi Arabia</a>, is the Wadi Hanifa watershed, a 4,000 square kilometer drainage that has become key to the capital's environmental sustainability. After many years of neglect, a long term reclamation plan was put underway, and is now being recognized worldwide for its size and aesthetic. The safe use of the river was one of the most visually compelling design features, but it was water reclamation, habitat restoration and industrial clean up throughout the river basin that really exemplifies how profound the project's scope is.

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Wadi Hanifa Wetlands

Years of laissez-faire development led to damaging floods, mounds of construction waste and polluted water in the basin that serves a burgeoning population that grows increasingly dependent on the source.

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Wadi Hanifa Wetlands

The plan, a joint venture between <a href="http://www.mtplanners.com/mtpwadi.html">Moriyama &amp; Teshima Planners Limited</a> and <a href="http://www.burohappold.com/BH/PRJ_BLD_wadi_hanifah.aspx">Buro Happold</a>, was to turn the basin into a thriving natural reserve that not only restored wildlife, but would provide for the community.

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Wadi Hanifa Wetlands

<a href="http://inhabitat.com/category/water/">Water quality</a> was paramount in the restoration for both the upstream water and for the city’s wastewater which is intended to be stored and reused.

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Wadi Hanifa Wetlands

To accomplish this, 1.25 million cubic meters of construction debris were removed and the haphazard roads and power lines were reorganized to reduce surface impact. Side water inlets are reclaimed or added to aid in flood control and support habitation.

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Wadi Hanifa Wetlands

Natural stone weirs have been installed to create a habitat for micro organisms and to increase oxygen levels to reduce <a href="http://en.wikipedia.org/wiki/Coliform_bacteria">chloroform bacteria</a>.

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Wadi Hanifa Wetlands

Being adjacent to the city, the basin is a major local and tourist attraction. As a result, recreational facilities were combined with habitat enhancement and <a href="http://inhabitat.com/top-6-life-saving-designs-for-clean-drinking-water/">water quality</a> infrastructure.

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Wadi Hanifa Wetlands

The park provides a place for residents to explore and cool down.

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Wadi Hanifa Wetlands

The large bio-remediation facility is a one of a kind design that recreates the complex habitat, which in turn is able to treat city and river water naturally.

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Wadi Hanifa Wetlands

The complex is also a large park which provides area to explore and interact with the water environment.

Wadi Bed Naturalized Parkland and Recreational and Interpretative Trail is a great example of how the two design challenges of water quality management and<a href="http://inhabitat.com/german-water-park-makes-wastewater-recycling-fun/"> public access</a> are weaved together.

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Wadi Hanifa Wetlands

The park's use will only increase over time, and it is intended to help provide one million cubic meters of water per day by 2021 in order to meet a third of the city’s total water demand.

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Wadi Hanifa Wetlands

The restoration project spans 120 km.

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Wadi Hanifa Wetlands

Water is the lifeblood of sustainable habitation, and no more so is it crucial than in desert societies. One of this year's winners of the Aga Khan Award for Architecture is not a building complex, but remarkably, an entire ecosystem. Located in Riyadh, the capital of Saudi Arabia, is the Wadi Hanifa watershed, a 4,000 square kilometer drainage that has become key to the capital's environmental sustainability. After many years of neglect, a long term reclamation plan was put underway, and is now being recognized worldwide for its size and aesthetic. The safe use of the river was one of the most visually compelling design features, but it was water reclamation, habitat restoration and industrial clean up throughout the river basin that really exemplifies how profound the project's scope is.